The 3G technology has become a predominant field of researches on such modern mobile communications that increasingly tend to provide multimedia services transmitted at a high rate. The 3rd Generation Partnership Project (3GPP) is devoted to put the Long Term
Evolution (LTE) system as the evolvement of the 3G system. Long Term Evolution-Advanced (LTE-A) is subsequent evolvement of the LTE technology, which is commonly referred to as 3.9G As compared with the 4G standard, all the technical indexes of the Long Term Evolution (LTE) except for the maximum bandwidth and the uplink peak rate, both of which are slightly inferior to the 4G standard, have satisfied the 4G standard.
In the LTE system, a Physical Random Access Channel (PRACH) is an uplink random access channel, and upon reception of a Fast Physical Access Channel (FPACH) response message, a User Equipment (UE) transmits a Radio Resource control (RRC) message over a PRACH channel according to indication information of a base station to set up an RRC connection. If there are a number of PRACH channels, then the UE will select corresponding one of the PRACH channels according to information indicated in the FPACH.
The LTE system configures an uplink PRACH channel so that one PRACH channel occupies 6 Physical Resource Blocks (PRBs) consecutive in frequency domain, where a primary parameter of the PRACH in time domain is the preamble format, and if the preamble format of the PRACH channel ranges from 0 to 3, then a channel frequency domain offset of the PRACH will be configured, where the channel frequency domain offset may have a direct influence upon a frequency domain position at which the UE transmits the uplink PRACH channel, and a frequency domain position at which the base station receives the uplink PRACH channel.
In the prior art, the channel frequency domain position of the PRACH is generally initialized in a cell, and then configured manually or by importing an initialization file, and since the channel frequency domain offset is configured before the cell is deployed, it may not be adjusted adaptively to the current communication environment of the cell.
The position at which the base station detects a preamble in the uplink is determined by the frequency domain position information of the PRACH configured by the base station, and if there is significantly noise floor rising in the frequency band, or there is strong interference busting in the frequency band, then if the power of the interference or the noise is higher than the power of a useful signal, then the base station may not detect and decrypt the preamble carried in the PRACH channel, so that the UE may not access the system, thus degrading an access success rate throughout the system.
In view of this, it is desirable to propose an effective technical solution to solve such a problem that the channel frequency domain position of the PRACH may not be adjusted adaptively to the current communication environment of the cell.